Post-activation depression in the human soleus muscle using peripheral nerve and transcutaneous spinal stimulation. (4th March 2015)

• Record Type: Journal Article
• Authors: Andrews, Jennifer C.; Stein, Richard B.; Roy, François D.
• Is Part Of: Neuroscience letters. Volume 589(2015)
• Page Start: 144
• Page End: 149
• Publication Date: 2015-03-04
• Subjects: H-reflex -- Root evoked potential -- Soleus -- Transcutaneous spinal stimulation -- Post-activation depression; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2015.01.041
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: Post-activation depression of the H-reflex and REP was studied at 25–200 ms intervals. Depression of a second response was induced by a conditioning H-reflex or REP. Recovery at rest was ∼30% as compared to during contraction. Recovery of the REP → H and H → H conditions were similar. The REP → REP condition showed the most depression. Abstract: Transcutaneous stimulation of the human lumbar spine can be used to elicit root-evoked potentials (REPs). These sensory-motor responses display notable similarities to the monosynaptic H-reflex. The purpose of this study was to compare post-activation depression of the soleus REP to that of the H-reflex, when conditioned by either an H-reflex or an REP. Paired pulses were delivered 25–200 ms apart and the recovery was characterized using three levels of stimulation. In all conditions, post-activation depression was reduced during contraction as compared to rest ( P < 0.001). REP doublets, delivered using an inter-pulse interval of 150 ms, recovered to 68 ± 8% of control during plantarflexion and 20 ± 6% of control at rest. During contraction, recovery of a second REP was 65% of the corresponding recovery for a second H-reflex. The recovery of an H-reflex was equivalent, when conditioned by either an H-reflex or an REP, even though the spinal stimulus activated and/or engaged more afferent and efferent fibers. Our results suggest that the additional elements activated by the spinal stimulus did not affect the recovery of the H-reflex. However, the transcutaneous spinal stimulus produced more inhibition when it was assessed using two low-intensity REPs ( P < 0.05) suggesting that the pathway mediating the spinally-evoked response was more susceptible to being inhibited.